Usually, it's because the sperm gets into the fallopian tube before the egg is released. Once there, the sperm wait for an egg to arrive. After fertilization, it can take 5-10 days for the fertilized egg to begin to attach itself to the lining of the uterus. Pregnancy begins when this happens.
The arrangement of spikes originally had no distinct name; the term Thagomizer was coined in 1982 by cartoonist Gary Larson in his comic The Far Side, and thereafter became gradually adopted as an informal term within scientific circles, research, and education.
Just because joking use of it can be sourced doesn't mean it should have an article. If this article is to be kept, it should be at the correct paleontological term, and Thagomizer a (silly, but valuable) redirect to it. â SMcCandlish [talk] [contrib] ã 00:38, 21 February 2007 (UTC)